1. Field of the Invention
The present invention relates to a device for improving fluidity of intake air entering a combustion chamber of an engine, and a manufacturing method of an intake port used to improve fluidity of intake air.
2. Description of the Prior Art
As generally known in the art, as a fluidity of a fuel-air mixture sucked in an engine increases, flame is easily propagated so that combustion performance of the engine is improved.
Recently, in order to increase the fluidity of the fuel-air mixture and thus to improve the combustion performance as described above, there is used a method in which air itself flows in a combustion chamber with strong rotation. In this case, a process is mainly used in which a shape of an intake port is controlled to form tumble flow.
FIG. 1 shows an air intake system of an engine for forming tumble flow according to the prior art. As shown in FIG. 1, the air intake system includes an air intake pipe 104 for inducting air into a combustion chamber 102, a bypass pipe 106 disposed in parallel with the air intake pipe 104, and a control valve 108 disposed within the air intake pipe 104 and serving to control flow of air through the air intake pipe 104.
In a mechanism for forming tumble flow in the combustion chamber 102 using the device shown in FIG. 1, flow of air through the air intake pipe 104 is controlled with the control valve 108. As a result, where air supplied through the bypass pipe 106 and air supplied through the air intake pipe 104 are different from each other in flow rate, a swirl is formed due to the different flow rate when air flows in the combustion chamber 102. Whether tumble flow is formed or not, the amount of the formed tumble flow and the like varies depending on an opening degree of the control valve.
However, since the variable tumble-generating device constructed and operated as described above must have the bypass pipe 106 separate from the prior air intake pipe 104, it has a problem of its installation space in relation with other parts and a problem of complexity of manufacture.
Furthermore, the separate bypass pipe 106 must include a plurality of bent portions in view of its structure. Owing to such bent portions, a large flow resistance is generated in air flowing through the inside of the bypass pipe 106, so that the bent portions act as a cause of a decrease in flow rate of the flowing air. For this reason, the bypass pipe is a little disadvantageous to achieve its original object for creating tumble by forming a flow of air of high flow rate using its narrow section area and creating a flow rate different from air flowing through the air intake pipe.